So long as they stood on the defensive, however, the French had the great advantage of a range of positions naturally formidable, and improved by some passable field-works. General de Curières de Castlenau, a particular star of the old aristocratic-military school, was unorthodox in one vital matter. In a study written in the spring of 1914,[74] he had concluded that the French concentration would be completed as soon as, or a little sooner than, the German. Nevertheless, he had declared for the strategical defensive; and, foreseeing a decisive battle on the Grand Couronné, the heights bordering the Gap of Charmes, and the west bank of the Mortagne, he had planned, for when the German attack should be worn down, the reaction north and south of the Forest of Vitremont which he was actually to conduct some months later. In this, Castlenau was one of the far-sighted few. The defensive idea favoured in the period when the military inferiority of France was most acutely felt had sunk into disrepute. “The system of offensive strategy, of ‘striking out,’ gained adepts, especially among the young officers,” says M. Hanotaux. “Certainly the system of a waiting strategy had not lost all its partisans: General de Castlenau represented a strong and reasoned doctrine when he advocated, for the east in particular, the offensive-defensive, and the preparation of a stand on the Meurthe at the outset, then on the Mortagne.” He was overborne in favour of the daring and gifted lieutenant and teacher who, in 1900, had insisted that “movement is the law of strategy,” that the shock must be sought, not waited for, and that, “in a war with Germany, we must go to Berlin by way of Mayence.”[75] Instead of leading to Mayence and Berlin, the French march upon Morhange and Sarrebourg had led back to the Gap of Charmes and the Grand Couronné. Tragically justified, Castlenau now had his chance. For the first time, the invaders found themselves faced by entrenchments, wire-fields, gun-pits, and observatories prepared as well as the time available had allowed.